Turbo bearing failure

I've lurked the forums a while but looking for some advice on a turbo failure issue. Any thoughts or opinions on the issue would be appreciated.

I've had twin turbos on my chevy LS3 for about 70k miles. Never had any issues with the turbos. I lost the bottom end and had the whole motor rebuilt. At the same time I moved over to some bigger turbos.

The turbos are based on a mitsu td06 center with a larger compressor wheel. I'm now on my 3rd rebuild of the turbos in less then 1000 miles. The ID of the exhaust side bearing is getting worn very quickly and the seal is looking a little polished. The compressor side bearings are no where near as worn as the exhaust side. The car will make a cloud of white smoke under boost but I don't see any smoke under regular driving. I have 3" exhaust (no cats) from each turbo into two magnaflow mufflers.